My 3200# cuda with a 4 speed 4:88 ran 11.84 @ 114.97 just a cam and valve springs all the rest was a stock 340
First time down the track
- Thread starter 67Cuda408
- Start date
-
My 3200# cuda with a 4 speed 4:88 ran 11.84 @ 114.97 just a cam and valve springs all the rest was a stock 340
Start with bringing the timing back to 32-34 (that is where my 410 stroker was happiest)....there are more than likely more issues, but it is a start. My guess is the heads don't flow anywhere near what you were told. That is a pretty unrealistic number from a stock head.
Things I would check:
Have you messed with the carb jetting yet? (Keep jetting up for best MPH, when it slows down back it up and you're set.)
What fuel pump?
Might want to do a leak down test.
For what its worth, my 410 stroker was 10.8:1 compression, a little bigger cam, heads that flowed 293 in a 3200# 67 Barracuda...it ran mid 10's, but would still do high 11's when I lifted a little before half track and coasted all the way through the 1/4 mile....something is DEFINITELY wrong big time.
I didn't read through all the post..... but...
with your weight, gears, stall, looks like you have around 300-310 hp. Drag Radials would move ya down to about a 13 flat with that speed. you need to find the 150 horses that's missing. I think the car should be mid 11's at 115 mph.
with your weight, gears, stall, looks like you have around 300-310 hp. Drag Radials would move ya down to about a 13 flat with that speed. you need to find the 150 horses that's missing. I think the car should be mid 11's at 115 mph.
moper
Well-Known Member
Was the engine actually on an engine dyno, or is this a figure from various simulators? There are huge differences between a simulator, real engine dyno, and an engine in a car at the track. The track is the only truth teller. Weight the car, use the MPH. I'd say it's probably 100hp less than you think.
As a point of comparison - an E body with a 422", my ported 496 heads, hydraulic cam (242@.050), 2200 convertor, with 3.23s runs 109mph on street radials, and is probably a solid 400lbs heavier.
As a point of comparison - an E body with a 422", my ported 496 heads, hydraulic cam (242@.050), 2200 convertor, with 3.23s runs 109mph on street radials, and is probably a solid 400lbs heavier.
- Joined
- Sep 2, 2008
- Messages
- 262
- Reaction score
- 112
Did you flash stall (test) the convertor?
I haven’t put the engine in the dyno so it is an estimation but given the specs of the parts used I don’t feel like that estimate would be 150hp off. I did leave very conservative for fear of losing traction but the discrepancy seems to large.
I have not flash stall tested the converter. How would I go about doing that?
I plan on doing a compression and leak down test maybe I’ve flat spotted a cam lobe? I’ll post what i find and appreciate all of your input and help finding the half an engine I lost.
I have not flash stall tested the converter. How would I go about doing that?
I plan on doing a compression and leak down test maybe I’ve flat spotted a cam lobe? I’ll post what i find and appreciate all of your input and help finding the half an engine I lost.
B3422w5
Well-Known Member
Where you leave the starting line at shouldnt make much if any difference. In the same evening racing two different classes i have left off the tbrake with chip at 4300, and left off the foot at 2000.
Car 60 footed and ran within a hundredth of the same.
To test, put the car in high gear moving just off idle and mash the gas. See where the needle went to on the tach
If he doesn't have a full manual valvebody that could be a problem
B3422w5
Well-Known Member
Good point
replicaracer43
Grumpy Old Man
- Joined
- Oct 10, 2008
- Messages
- 6,051
- Reaction score
- 7,867
Wouldn't explain his poor MPH
he was talking about testing the convertor, put it in high gear and floor it and see where the tach goes, but if it shifts into first unexpectedly who knows which way it might go.
Believe it or not, your mph won’t change much from traction loss. You can either spin off the line or hook and your mph will be nearly identical. The only thing that really changes is your ET. That’s the beauty of the track is that your mph will always tell you the power you are actually making. Doesn’t matter if you hooked well or not.
With a manual valve body, you would put it in 3rd gear at a slow speed like 30-40 mph and nail the throttle from a near idle. Where the tach stops and holds while the car accelerates tells you the stall your converter is providing with your combination. Without the manual valve body, the car will kick down a gear and will rev past your stall speed so that will be more difficult to figure out as previously stated by Brian.
But keep like you’re doing and get the easy things checked out first. Back the timing up, check the compression and/or perform a leakdown test, and read the plugs (there’s an excellent write up on 4secondsflat). See that those things are in order and then continue the process of elimination.
Exhaust? First time on the drag strip back in 86. 71 RR with a low comp 440 with 292 Comp and headers. 3.23 gears. 14.90s at 93 mph. The next time I went to the track I uncorked the exhaust and went 14.10s at 102 mph. The exhaust was two inch pipe shoved into 3 to 2.5 collector reducers and long glasspacks. So , I figure that weenie exhaust was costing me about 90hp.
moper
Well-Known Member
Simulators are not even close a lot of times, sort of in the neighborhood some of the time, and dead on rarely. Weight and MPH. Gearing, traction, doesn't matter. Track results do not lie - so you are down on power. Question becomes "why"?
If we go on head flow at a little shy of max lift - in the mid 400 range at the valve, you have to be getting 225cfm to get 450hp. The stock LA heads will flow close to that. So I'd say there's a mechanical problem (valve job, assembly, cam timing, etc) or a problem with the porting. If I had to guess. This assumes the timing curve, ignition, and carb are all set properly. Do a leak down. DO a compression test. See what the numbers tell you.
If we go on head flow at a little shy of max lift - in the mid 400 range at the valve, you have to be getting 225cfm to get 450hp. The stock LA heads will flow close to that. So I'd say there's a mechanical problem (valve job, assembly, cam timing, etc) or a problem with the porting. If I had to guess. This assumes the timing curve, ignition, and carb are all set properly. Do a leak down. DO a compression test. See what the numbers tell you.
furrystump
Well-Known Member
- Joined
- Nov 13, 2004
- Messages
- 2,103
- Reaction score
- 1,700
As stated before timing, not to pile on but my Dwayne Porter x heads flow 278-284 which is a pretty much all out effort with an x head. What mufflers? I run a small tire, so this might help. I load the converter until the car starts climb on the suspension. Then leave on whatever light works for you. Then release the brake while holding the throttle steady, the car will begin to roll, just as the nose starts to drop I roll into the throttle. The carb might be small. I have run a 825 mighty demon on my car. Thats 825 crm wet flow. I have run 12.24 with your Stroke/compression and your stated head flow numbers. Solid flat tappet, .555 lift. 1.71 60’
furrystump
Well-Known Member
- Joined
- Nov 13, 2004
- Messages
- 2,103
- Reaction score
- 1,700
IIRC, flash stall and stall are two different values. In gear brake hard enough car doesnt move, feed it throttle until the rpm’s stop increasing is the stall rpm. Flash is just slightly higher. You hammer the throttle quickly until the engine stops gaining rpm. The rpm’s flash higher the settle down to steady stall. The highest momentary rpm is the flash. The steady rpm is stall. Spend the shortest amount of time possible during the test and the car may push through the brakes. You would be surprised how much heat this will generate. I don’t think this is converter issue
Don’t view it as piling on at all. Appreciate all the help. I already have a spring and bushing kit to recurve my MSD pro billet dist cause even thought that’s not the whole issue it’s probably part of it. I have flowmaster 40s through 2.5” exhaust. I am running a 750 cfm Holley so that may be hurting too. And info is welcome and appreciated.
furrystump
Well-Known Member
- Joined
- Nov 13, 2004
- Messages
- 2,103
- Reaction score
- 1,700
I ran a pro billet for a while, but had to change for my class. Due to my cam overlap I used to run 24 initial and 34 total. No vacuum. I bought the 10 deg bushing from FBO to be able to run that much initial. Now I just run the jegs billett distributor that you adjust the mechanical advance using plastic “keys”. I have found small block open chamber heads to be pretty sensitive to total timing. 2 degrees off and you will see it!
Okay well then I’m WAY off for total timing. I’m at 40 total currently. Didn’t feel like it was pinging though but clearly I could be wrong.
furrystump
Well-Known Member
- Joined
- Nov 13, 2004
- Messages
- 2,103
- Reaction score
- 1,700
Tire pressure, on clean pavement spin the tire. You want a nice even black mark all the way from left to right. If light in the middle go up two pounds, if they are light on the edges go down 2 pounds. Keep at it until you have even color. Which will get you close. Then from that point once the car becomes consistent you can play with the pressures. See what gives you the best 60’
Oe style mechanical pump, Summit -6 hose to filter and Holley 750 vacuum secondary carb.
The carb is not hurting too much....my mid 10 second 410 stroker used a 750 dp...just sayn.
-
